SU584763A3 - Method of purifying polymethylenepolyphenylpolyisocyanate - Google Patents

Description

Cess is carried out under pressure of 1.40-4.20 kg / cm for 10-5O minutes. The best results are achieved if 10-90% monochlorobenzene is distilled off during the purification process. The proposed purification method for polymethyl len-polyphenyl polyisocyanate reduces the content of hydrolysable chlorine, eliminates the formation of a foul odor under the conditions of polyresin production, and also simplifies the process by eliminating the stage of purging the product with an inert gas in a counter-flow column. Example. The following apparatus and methodology is used in a series of experiments at different temperatures and laziness, using ball raw materials. The raw material used is a solution (21.4 wt.%) Of polymethylene polyphenipacti isocyanate (containing approximately 50 wt.% Methylenebis- (fenis isocyanate), the remaining mixture. Represents oligomers with higher functionality) in chlorobenzene, taken in An aliquot of Loli:;. r: ™: r: -z Zei of the raw material is evaporated under reduced pressure, and it is established that it has cnenvm properties: Next Equivalent amount of 11% cyanate% ECC obtained by heating% Hydrolyzable C% Total Hydrolyzed content Ct Odor test a and b c flax Tests for the presence of impurities (which ... lead to undesirable odors in the preparation of foam rubber using formulations catalyzed by basic catalysts) are carried out in one of two a) 2 ml of an isocyanate sample is stirred for 30 seconds with 2 ml of 25% aqueous sodium hydroxide solution and the mixture is left to STAND. with freely installed

Table 1 over the vessel lid for 1 hour. By the end of this time, the mixture is checked for traces of odor (carbilamic smell). b) 500 g of an isocyanate sample is used to obtain polyurethane foam rubber using a conventional industrial neiao-pe chain using catalysis with triethi pep diamine. After a day, the resulting foam rubber is cut and tested for odor. In each experiment, the indicated raw materials are fed at a speed of 100-125 g / min to an autoclave with a capacity of 3.785 liters, equipped with a detachable tube for the selection of a low boiling overhead to a refrigerator. Speed, with vn-mr, g. The purified, non-distilled isocyanate is withdrawn from the autoclave, adjusted according to the speed at which the low boiling overhead is sampled to keep the liquid in the autoclave with a weight of 1400 g: The equipment is provided with appropriate pressure reducers so that any desired pressure can be maintained pnc, td, to remove solvent and subjected to analyzes provided by table. 1. At the same time, an aliquot fraction is taken from the condensate formed from the low-boiling i-th overhead stream, which is evaporated to remove the solvent and subjected to the analyzes presented in Table 1. From the data of Table 1 it can be seen that the purified polyisocyanate extracted from the autoclave in each of the experiments has a markedly reduced acidity and hydrolyzable chloride content and shows the best results when tested for the presence of odor. In contrast to this, the low-boiling point, a substance selected as an overhead stream, has an increased content of hydrolysable chloride and acidity. The residence time presented in Table 1 for each experiment is the calculated average time during which a portion of the supplied polyisodianate is in the autoclave.

Fluid temperature

218-212-221 in the autoclave, C

149 226-23 - 207-218.

183

five

The residue in the autoclave:

Equivalent amount of isocyanate

% MHB

(according to distillation)

% carried by heating

% Hydrodizable SK

% Of the total content of hydrolyzable CE

Low boiling overhead:% MHB

Remainder freed

from MHB% neb, get

-to

MHB - monochlorobenzene

“Method a.

EXAMPLE 2. Other experiments were carried out using the same apparatus and technique as in Example 1, but replacing the raw material. A polyisocyanate containing 21.1% by weight of polymethylene polyphenylpolyisocyanate (diisocyanate content of approximately 5O%) in monochlorobenzene is used as a raw material. An aliquot of this raw material is evaporated under reduced pressure to remove the solvent, and the polyisocyanate sample obtained in this way has the following analysis data:

Equivalent amount

isocyanate131,5

% NA received

when heated 0,16

% Hydrolyzable, 18

Continued table. one

133.9 133.7133.2 132.7 -142.5 138.0

22,021,016,1 3,74,111,9

0.034 0.076 0.047 O, 022

0.021 0.068 0.13 0.057 0.053 0.052

0.16

0, ZO 0,35 0,19

0.28

98.1 98.7 93,596.3 97.3

35

% Total Content

hydrolyzable, 49.

Smell by test

a and b

Test 7 was carried out at atmospheric pressure and low temperature (118 ° C), and test 8 under pressure 1 (758 kg / cm and at a temperature of 196-204 C. As can be seen from the data of these experiments, presented in Table 2, test 8 according to The invention leads to a significant decrease in acidity and hydrolyzable chlorine content and odor removal. Experiment 7, carried out under conditions that do not correspond to the proposed one, does not substantially change the acidity, the level of hydrolysable chlorine, and the odor level caused by impurities.

% Total content of hydrolyzed CE

boiling overhead:% MHB

The residue freed from MHB% HC6, obtained by heating

% Hydrolyzed CE

% Total Hydrolyzed CE

Smell of bottom residue

X

autoclave According to method a, PRI me R 3. The equipment and method described in example 1 is modified with nepoj water of unreacted bottom fraction in the upper part of the column (1.829 mx 0.051 m) filled with ceramic nozzle of diameter type O, 3 cm The column cleanness is treated under the same pressure and temperature conditions as the isotane in the automat. A low-boiling overhead stream from the autoclave is fed into the inlet opening at the lower end of the packed column, and the back-up upper stream is removed from the upper part of the column. The experiments presented in table. 3, is carried out using the above apparatus and technique, using an average fluid delay of 730 g in an autoclave. Experiments 9-12 were carried out using as a raw material polymethylene polyphenyl polyisocyanate having the following properties:% MHB79.3 The equivalent effective amount of isocyanate. 130.7

 8 Table 2

0.44

0.26 8.6 97.6

2.14

1.50 1.63 2.50

1.63

3.64% HC6, obtained by heating0, 18% of the total content of hydrolysable, 55 Odor according to tests a and b Strong Experiments 13-17 are carried out using polymethylene-polyphenyl-poly- in the raw material | cyanate, having the following properties:% MHB81.5 Equivalent amount of isocyanate, 131.7% carried, when heated, 0.17% Total content of Hydrolyzed SS0.50 Odor by test a and b Strong For each experiment, an aliquot fraction extracted from unregulated The bottom fractions that remain in the autoclave in the column are evaporated to dryness and analyzed. The results are presented in table. From the above one can see a noticeable decrease in acidity, the content of hydrolyzable chlorine and odor caused by impurities, in the substance that remains in the autoclave and at the bottom of the packed column. This is achieved only with a very slight increase in the equivalent amount of isocyanate (corresponding to noiepe less than 2% of isocyanate groups).

eleven

12

1.3

14

15

Claims (1)

1. US patent N 3857871, cl. 260453, SP, 1974.